[TowerTalk] Professional attachment hard line to Rohn tower

[Dick Green WC1M]

When I built my 110' Rohn 55 tower, I acquired a handful of Andrew cable clips for 1-5/8", but decided not to run it up the tower (it's a bear to work with, especially inside a Rohn 55 tower.) I considered getting clips for the 7/8" runs, but on inspecting the 1-5/8" clips I realized that I would need to find a way to attach them to the tower legs which I would not under any circumstances drill, and the process would take much longer than zip ties and tape.

Last week I hoisted a feedline consisting of 80 feet of 7/8" spliced to 40 feet of 1/2". It joins two other 7/8" runs and a 1/2" run, all of which go up inside the tower and each of which is attached at the top with its hoisting grip and down the run with UV-rated zip ties covered with electrical tape about every three or four feet. During the operation, I inspected the zip tie/tape points for the existing cables and found they're in perfect shape after eleven years in the air.  I really don't think the clips are necessary for an amateur installation and just make the job more difficult and time consuming. I would, however, use them on hardline larger than 7/8".

I highly recommend using hoisting grips, especially for heavier cables. Per the instructions, it's best to put the grip down the cable several feet below the top end, and attached the portion above the grip to the rope (the instructions show little rope loops but I used tape.) If the grip is too close to the connector it'll be hard to attach a feedline and waterproof the connection. It's also necessary if the run has to go around a pair of rotor plates (i.e., has to emerge from inside the tower to go around the rotor plates.) I used a high-load carabiner to attach the rope to the hoisting grip. Longer (heavier) runs probably require a shackle. When each cable reached its destination, I attached the hoisting grip to a rung with a hose clamp. Probably better to attach the grip to a leg, but I can't recall now why I didn't do that. I think the downward force on the rung is minimal now that the cables are zip-tied and taped all the way down.

BTW, that combo run I hoisted last week turned out to be bad. It tested fine on the ground and I haven't yet determined what happened. I suspect the splice between the two cables is the problem, though I took great pains to reinforce it. Could be that my helpers damaged the 1/2" or the splice when they carried the roll to the tower. I got all the hardline, which was either used or spool ends, for free years ago and it's been in storage in my garage. The 1/2" isn't the greatest hardline -- it's RFS RG-331/U, 50-ohm with aluminum outer conductor. I actually have the correct connectors for it, but they're nowhere near as good as the Andrew connectors I have on my LFDF4-50 runs. The other possibility is that there was water in the 7/8" and it's all run down and pooled at the bottom connector. I saw some water when I removed the caps I had put on it prior to storage and attempted to drain it out by walking along the cable and holding it high over my head (as you would drain a garden hose.) Could be that I didn't get all the water out. Cautionary tale: there are risks with using leftover and used hardline. My plan is to connect a dummy load at the bottom, climb the 30 feet or so to the splice and open it up. That way I can determine which of the two cables is bad. If it's the 1/2", I'll probably take it down and fix or replace it. If it's the 7/8", I'll remove the bottom connector and see if any water comes out.

Sorry for the long reply...

73, Dick WC1M

-----Original Message-----
From: Steve Maki <lists at oakcom.org> 
Sent: Sunday, July 8, 2018 9:16 PM
To: towertalk <towertalk at contesting.com>
Subject: Re: [TowerTalk] Professional attachment hard line to Rohn tower

On commercial towers we use a hoisting grip (one per cable) and a shackle (also one per cable) to support the dead weight of the cable, and appropriately sized snap-ins all the way down to keep the cables from flapping & flopping around too much in the wind. Of course the snap-ins have to have a place to snap in to, which is normally a
*waveguide* ladder (should be called a cable ladder now-days), or individual brackets of some sort that have 3/4" holes to accommodate the snap-ins. Like *cluster* brackets, *triangles*, *box brackets*
*T-brackets* or other items like that. And those items have to be mounted somehow on tower legs or tower horizontals or tower diagonals.

However, I don't really recommend the snap-ins for ham use on smallish towers (up thru R65). It's way overkill and not appropriate in most cases.

The hoisting grip is a good idea, as it fully prevents gradual cable slippage which will cause grief at some point. But I'd recommend just doing a nice job of taping the cables down the leg(s) or down the middle of a face.

Current thinking about common mode currents usually suggest running the feedlines (and everything else) up *inside* the tower as a weapon against the dark side. I agree with this.

-Steve K8LX

On 07/08/18 16:03 PM, CEPitts wrote:

> Want to attach 1/2" and or 7/8" hard line to Rohn tower specifcally 
> Rohn
> 55 on one tower face horizontal brace or the tower leg and  want to 
> know if anybody has done this with brackets or some sort of 
> attachments from a 3rd party manufacturer of said brackets or 
> hardware? A search of the Rohn catalog did not seem to reveal any sort 
> of hardware available from them.
> 
> Has anybody else found a source for such a thing and a fairly easy 
> efficient install for running the hard line up the tower? Similar to 
> the neat arrangement we all see on commercial installs such as cell sites, etc.
> 
> I can go with the old standby of 33 tape, black ties wraps etc. 
> however if possible I would like to install the clamping material to 
> hold the hard line securely in place as it goes up the tower and be done with it.
> 
> Thanks Charles K5OF